1. Field of the Invention
The invention relates to water-soluble crosslinked copolymers, to a process for preparing the copolymers by free-radical polymerization of vinylimidazoles, N-vinylamides, N-vinyloxazolidone, N-vinyltriazole or mixtures of said monomers, with at least one monomer which acts as crosslinker and has at least 2 non-conjugated ethylenic double bonds in the presence of polymerization regulators, and the use of the copolymers as additive to detergents and cleaners.
2. Description of the Background
DE-A 32 09 224 discloses the preparation of insoluble polymers of low swellability from basic vinylheterocycles and their copolymers with up to 30% by weight of copolymerizable monomers and 0.1-10% by weight of crosslinkers in aqueous medium in the absence of initiators. As is evident from the comparative example in this publication, the polymerization of 100 parts by weight of N-vinylimidazole and 2 parts by weight of N,N'-methylenebisacrylamide in aqueous solution using azoisobutyronitrile as polymerization initiator results in firm gels.
The copolymerization of vinylheterocycles with crosslinkers in aqueous solution in the presence of free-radical initiators always results in gel formation, see the comparative example in DE-A 40 00 978. As is also evident from this reference, polymerization of a vinylheterocycle with a crosslinker and with exclusion of oxygen and of polymerization initiators results in water-insoluble copolymers which can be used, for example, to remove heavy metal ions from wine.